Ancient Craters of Southern Rhea . ... Credit Copyright: Cassini Imaging Team , SSI , JPL , ESA , NASA Explanation: Saturn's ragged moon Rhea has one of the oldest surfaces known. ... Like Earth's Moon , Rhea's rotation is locked on Saturn, and the above image shows part of Rhea's surface that always faces Saturn. Rhea's leading surface is more highly cratered than its trailing surface. ... Cassini swooped past Rhea last month and captured the above image from about 350,000 kilometers away. ...